Problem I am having is I used a Corsair H105 for its cooling solution. It works great, idle at 28C, doesn't go over 40C even under top load. It's the fan noise!

The motherboard aux fan 2 connector wants to spin the second radiator fan at 1800 RPM. Using MSI's control software, I got it down to 1500RPM, but its still too loud (to me). Speed fan cannot control it, nor can Corsairs software.

Other than putting a dedicated hardware fan controller in, any one have any software suggestions to get it down to 800 RPM?

Get a PWM fan if your board is PWm compatible. PWM is 4 pins on your fans and board. You can then set your fans to down to 5% I believe in PWM settings in your BIOS. Even though I use PWM, I still use this in all my builds. Just works.